US8161729B2 - Exhaust purification system for internal combustion engine and control method of the exhaust purification system - Google Patents

Exhaust purification system for internal combustion engine and control method of the exhaust purification system Download PDF

Info

Publication number
US8161729B2
US8161729B2 US12/280,564 US28056407A US8161729B2 US 8161729 B2 US8161729 B2 US 8161729B2 US 28056407 A US28056407 A US 28056407A US 8161729 B2 US8161729 B2 US 8161729B2
Authority
US
United States
Prior art keywords
catalytic converter
hydrogen concentration
fuel ratio
upstream
purification system
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Fee Related, expires
Application number
US12/280,564
Other versions
US20090019832A1 (en
Inventor
Kenji Katoh
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Toyota Motor Corp
Original Assignee
Toyota Motor Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Toyota Motor Corp filed Critical Toyota Motor Corp
Assigned to TOYOTA JIDOSHA KABUSHIKI KAISHA reassignment TOYOTA JIDOSHA KABUSHIKI KAISHA ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: KATOH, KENJI
Publication of US20090019832A1 publication Critical patent/US20090019832A1/en
Application granted granted Critical
Publication of US8161729B2 publication Critical patent/US8161729B2/en
Expired - Fee Related legal-status Critical Current
Adjusted expiration legal-status Critical

Links

Images

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N11/00—Monitoring or diagnostic devices for exhaust-gas treatment apparatus, e.g. for catalytic activity
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/021—Introducing corrections for particular conditions exterior to the engine
    • F02D41/0235—Introducing corrections for particular conditions exterior to the engine in relation with the state of the exhaust gas treating apparatus
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/14—Introducing closed-loop corrections
    • F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
    • F02D41/1444—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2550/00—Monitoring or diagnosing the deterioration of exhaust systems
    • F01N2550/02—Catalytic activity of catalytic converters
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
    • F01N—GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR MACHINES OR ENGINES IN GENERAL; GAS-FLOW SILENCERS OR EXHAUST APPARATUS FOR INTERNAL COMBUSTION ENGINES
    • F01N2560/00—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics
    • F01N2560/02—Exhaust systems with means for detecting or measuring exhaust gas components or characteristics the means being an exhaust gas sensor
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/14—Introducing closed-loop corrections
    • F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
    • F02D41/1444—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
    • F02D2041/147—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being a hydrogen content or concentration of the exhaust gases
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D41/00—Electrical control of supply of combustible mixture or its constituents
    • F02D41/02—Circuit arrangements for generating control signals
    • F02D41/14—Introducing closed-loop corrections
    • F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
    • F02D41/1439—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the position of the sensor
    • F02D41/1441—Plural sensors
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A50/00—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE in human health protection, e.g. against extreme weather
    • Y02A50/20—Air quality improvement or preservation, e.g. vehicle emission control or emission reduction by using catalytic converters
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/12—Improving ICE efficiencies
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/10—Internal combustion engine [ICE] based vehicles
    • Y02T10/40—Engine management systems

Definitions

  • the present invention relates to an exhaust purification system for an internal combustion engine and a control method of the exhaust purification system.
  • an oxygen concentration sensor is disposed upstream of a catalytic converter in the engine exhaust system to detect an oxygen concentration in the exhaust gas and estimate the optimum air-fuel ratio based on the detected oxygen concentration.
  • the present invention provides an exhaust purification system for an internal combustion engine and a method of controlling the exhaust purification system, which allow a more accurate estimation of the optimum air-fuel ratio when the ratio is richer than the stoichiometric ratio.
  • a first aspect of the invention relates to an exhaust purification system for an internal combustion engine.
  • the exhaust purification system for an internal combustion engine has an upstream hydrogen concentration sensor disposed upstream of a catalytic converter in the engine exhaust system to detect the hydrogen concentration in the exhaust gas and estimate an optimum air-fuel ratio based on the detected hydrogen concentration.
  • the catalytic converter is a three-way catalytic converter and a downstream hydrogen concentration sensor is disposed downstream of the three-way catalytic converter. Also, when a measured or an estimated temperature in the three-way catalytic converter is lower than a prescribed temperature, the degree of deterioration of the three-way catalytic converter may be estimated based on the difference between upstream and downstream hydrogen concentrations detected by the upstream and downstream hydrogen concentration sensors, respectively.
  • the catalytic converter is a three-way catalytic converter and the downstream hydrogen concentration sensor is disposed downstream of the three-way catalytic converter.
  • the measured or estimated temperature in the three-way catalytic converter is equal to or higher than the prescribed temperature and the air-fuel ratio in the exhaust gas entering the three-way catalytic converter is equal to or richer than a stoichiometric ratio
  • sulfur poisoning of the three-way catalytic converter may be determined based on the difference between the upstream and downstream hydrogen concentrations detected by the upstream and downstream hydrogen concentration sensors, respectively.
  • the measured or estimated temperature in the three-way catalytic converter may be controlled to remain equal or higher than the prescribed temperature, while the air-fuel ratio in the exhaust gas entering the three-way catalytic converter is controlled to remain equal to or richer than the stoichiometric ratio.
  • the air-fuel ratio in the exhaust gas entering the three-way catalytic converter may be controlled to be leaner than the stoichiometric ratio.
  • the exhaust purification system according to the first aspect of the invention may further include an oxygen concentration sensor disposed upstream of the catalytic converter in the engine exhaust system.
  • an estimation of the optimum air-fuel ratio may depend on the hydrogen concentration sensor.
  • an estimation of the optimum air-fuel ratio may depend on the oxygen concentration sensor.
  • the exhaust purification system according to the first aspect of the invention may have no catalytic converter disposed upstream of the upstream hydrogen concentration sensor.
  • a second aspect of the invention relates to a method of controlling the exhaust purification system for an internal combustion engine.
  • the control method includes: detecting the hydrogen concentration contained in the exhaust gas upstream of a catalytic converter, disposed in the engine exhaust system; and estimating the optimum air-fuel ratio based on the detected hydrogen concentration.
  • the hydrogen concentration in the exhaust gas upstream of the catalytic converter increases more noticeably. Therefore, the detection of the hydrogen concentration in the exhaust gas with the upstream hydrogen concentration sensor disposed upstream of the catalytic converter in the engine exhaust system permits a more accurate estimation of the optimum air-fuel ratio, when the ratio is richer than the stoichiometric ratio.
  • the catalytic converter may be a three-way catalytic converter and the downstream hydrogen concentration sensor may be disposed downstream of the three-way catalytic converter.
  • a water vapor reforming reaction occurs in which hydrocarbons in the exhaust gas react with water vapor.
  • a water gas-shift reaction occurs in which carbon monoxide in the exhaust gas reacts with water vapor.
  • hydrogen is formed as a product in both reactions.
  • the difference between the upstream and downstream hydrogen concentrations detected by the upstream and downstream hydrogen concentration sensors, respectively indicates the activity of the aforementioned water vapor reforming reaction and water gas-shift reaction.
  • the degree of deterioration of the three-way catalytic converter may be estimated.
  • the catalytic converter may be a three-way catalytic converter and the downstream hydrogen concentration sensor may be disposed downstream of the three-way catalytic converter.
  • the measured or estimated temperature in the three-way catalytic converter may be controlled to remain equal or higher than the prescribed temperature, while the air-fuel ratio of the exhaust gas entering the three-way catalytic converter may be controlled to remain equal to or richer than the stoichiometric ratio.
  • the three-way catalytic converter continues to produce SO X emissions.
  • the SO X emissions react with hydrogen to form hydrogen sulfide, which is released to the air and possibly produces an offensive odor.
  • the air-fuel ratio of the exhaust gas entering the three-way catalytic converter is controlled to be leaner than the stoichiometric ratio to reduce the SO X emissions from the three-way catalytic converter even if SO X is stored therein.
  • FIG. 1 is a schematic diagram of an exhaust purification system for an internal combustion engine according to one embodiment of the invention.
  • FIG. 2 is a graph illustrating changes in hydrogen and CO concentrations versus air-fuel ratio.
  • FIG. 3 is a flowchart of a control process for the exhaust purification system for an internal combustion engine according to the embodiment of the invention.
  • FIG. 1 is a schematic diagram of an exhaust purification system for an internal combustion engine according to one embodiment of the invention.
  • a three-way catalytic converter 1 is disposed in the engine exhaust system.
  • An upstream hydrogen concentration sensor 2 is disposed upstream of the three-way catalytic converter 1 .
  • a downstream hydrogen concentration sensor 3 is disposed downstream of the three-way catalytic converter 1 .
  • the internal combustion engine is predominantly designed to perform a homogenous combustion process with the stoichiometric ratio.
  • the three-way catalytic converter 1 is designed to purity the exhaust gas burned at the stoichiometric ratio in a desired manner. However, under a high-load or high-speed operating condition, the air-fuel ratio may be enriched with respect to the stoichiometric ratio to increase engine output. Likewise, under a low-load or low-speed operating condition, the air-fuel ratio may be made leaner with respect to the stoichiometric ratio to reduce fuel consumption. Under these conditions, an O 2 storage capacity of the three-way catalytic converter 1 helps maintain the air-fuel ratio in the exhaust gas within the three-way catalytic converter 1 at around the stoichiometric ratio.
  • the oxygen concentration sensor is disposed in the engine exhaust system to detect the oxygen concentration of the exhaust gas and estimate the optimum air-fuel ratio based on the detected oxygen concentration.
  • the oxygen concentration in the engine exhaust system is almost zero when the air-fuel ratio is richer than the stoichiometric ratio. Under such condition, the oxygen concentration varies more slightly than the air-fuel ratio, which makes an accurate estimation of the optimum air-fuel ratio more difficult.
  • a solid line in the graph of FIG. 2 illustrates a relationship between air-fuel ratio and hydrogen concentration.
  • the graph shows, in the range of richer air-fuel ratio than the stoichiometric ratio, as the air-fuel ratio is richer (as the air-fuel ratio decreases), the hydrogen concentration increases more noticeably. Thus, the changes in hydrogen concentration are more apparent than the corresponding change in the air-fuel ratio. Therefore, in the embodiment of the invention, the optimum air-fuel ratio is estimated based on the hydrogen concentration in the exhaust gas, which is detected by the upstream hydrogen concentration sensor 2 . In this embodiment, the optimum air-fuel ratio is more accurately estimated of particularly when the air-fuel ratio is rich. Based on this accurate estimation, the amount of fuel to be injected may be controlled to obtain the desired air-fuel ratio.
  • the estimation of the optimum air-fuel ratio may be based on the hydrogen concentration detected by the upstream hydrogen concentration sensor 2 .
  • the oxygen concentration sensor is also disposed upstream of the three-way catalytic converter 1 to detect the oxygen concentration in the exhaust gas. The detected oxygen concentration is more noticeable when the air-fuel ration is leaner (as the air-fuel ratio increases). In other words, the oxygen concentration shows greater changes than the air-fuel ratio does.
  • the estimation of the optimum air-fuel ratio may be based on the oxygen concentration detected by the oxygen sensor.
  • a water vapor reforming reaction occurs in which hydrocarbons in the exhaust gas react with water vapor to form hydrogen, as shown in formula (1).
  • a water gas-shift reaction occurs in which carbon monoxide in the exhaust gas reacts with water vapor to form hydrogen, as shown in formula (2).
  • a catalytic converter is not disposed upstream of the upstream hydrogen concentration sensor 2 .
  • SO X in the exhaust gas reacts with barium or potassium contained in the three-way catalytic converter 1 and the SO X is stored therein (hereinafter called as sulfur poisoning).
  • This not only lowers the function of the noble metal catalyst contained in the three-way catalytic converter 1 , thus increasing the temperature at which the activation occurs, but also lowers the O 2 storage capacity of ceria contained in the three-way catalytic converter 1 .
  • the three-way catalytic converter 1 which stores the SO X , releases SO X if the temperature in the three-way catalytic converter 1 is equal to or higher than a prescribed temperature and the oxygen concentration in the three-way catalytic converter 1 decreases.
  • the high exhaust gas temperature causes the temperature in the three-way catalytic converter 1 to increase to or exceed the prescribed temperature.
  • the air-fuel ratio is equal to or richer than the stoichiometric ratio, under which the oxygen concentration in the exhaust gas decreases. Thereby, SO X is released automatically from the three-way catalytic converter 1 .
  • the upstream and downstream hydrogen concentration sensors 2 and 3 are used to determine the extent of deterioration of the three-way catalytic converter 1 or to solve the sulfur poisoning in accordance with the flowchart shown in FIG. 3 .
  • step S 101 determines whether a measured temperature T (estimated temperature) in the three-way catalytic converter 1 is equal to or higher than a prescribed temperature T 1 . If the determination is false, the three-way catalytic converter 1 will not release SO X . Then, the process goes to step S 102 to calculate a difference C between the upstream and downstream hydrogen concentrations C 1 and C 2 detected by the upstream and downstream hydrogen concentration sensors 2 and 3 , respectively.
  • the difference C depends on the amount of hydrogen in the aforementioned water vapor reforming and water gas shift reactions.
  • step S 103 determines whether a value, which is obtained by correcting the difference C between the upstream and downstream hydrogen concentrations C 1 and C 2 with a correction coefficient, k, is equal to or lower than a prescribed concentration D.
  • a dotted line in FIG. 2 illustrates a relationship between air-fuel ratio and CO concentration.
  • the difference C corrected with the correction coefficient k is independent of the amounts of CH 2 and CO currently contained in the exhaust gas, and the current temperature of the three-way catalytic converter 1 .
  • the difference C is inversely proportional to the current degree of deterioration of the three-way catalytic converter 1 .
  • the deterioration of the three-way catalytic converter 1 is determined directly from the oxidation-reduction reaction that occurs in the three-way catalytic converter 1 , such as the water vapor reforming reaction and water gas-shift reaction. This ensures more accurate determination of the deterioration of the three-way catalytic converter 1 , compared to the indirect determination from, for example, a decrease in O 2 storage capacity.
  • step S 101 determines whether the upstream and downstream hydrogen concentrations C 1 and C 2 are equal to or richer than the stoichiometric ratio. Therefore, if sulfur poisoning of the three-way catalytic converter 1 has occurred, it produces SO X emissions.
  • step S 106 determines whether or not the difference C between the upstream and downstream hydrogen concentrations C 1 and C 2 , which is calculated in step S 105 , is approximately equal to a hydrogen concentration C′ based on the amount of hydrogen formed by the water vapor reforming reaction and the water gas-shift reaction.
  • the hydrogen concentration C′ is estimated by taking into account the amounts of CH 2 and CO currently contained in the exhaust gas, the current temperature of the three-way catalytic converter 1 , and the current degree of deterioration of the catalytic converter 1 .
  • the true determination in step S 106 indicates that there is no hydrogen being consumption through the formation of hydrogen sulfide. In other words, it is determined whether the three-way catalytic converter 1 is not releasing SO X .
  • step S 106 If the determination in step S 106 is true, it is determined that sulfur poisoning of the three-way catalytic converter 1 has not occurred. The process ends the determination in accordance with the flowchart, as shown in FIG. 3 .
  • the air-fuel ratio is not necessarily enriched or leaned, and the amount of oxygen stored in the three-way catalytic converter 1 does not excessively fluctuate, as will be discussed below.
  • step S 106 a false determination in step S 106 indicates that hydrogen is being consumed to form hydrogen sulfide. In other words, it is determined that sulfur poisoning of the three-way catalytic converter 1 has occurred because to the release of SO X . Then, in accordance with the flowchart, the process goes to step S 107 to determine whether the vehicle has stopped. If the determination is false, that is, the vehicle is in motion, the process goes to step S 108 to enrich the air-fuel ratio with respect to the stoichiometric ratio, so that the three-way catalytic converter 1 continues to release SO X . However, hydrogen sulfide, which is formed while the vehicle is moving, does not enter the interior of the vehicle.
  • step S 107 the process goes to step S 109 to lean the air-fuel ratio to reduce SO X emissions. Thereby, hydrogen sulfide formation is less likely to occur.
  • the upstream hydrogen concentration sensor 2 is designed to detect the upstream hydrogen concentration C 1 in the three-way catalytic converter 1 .
  • the upstream hydrogen concentration C 1 may be determined based on the optimum estimated air-fuel ratio. For example, when the air-fuel ratio is leaner than the stoichiometric ratio, the oxygen concentration sensor may be used to estimate the upstream hydrogen concentration C 1 .

Abstract

An exhaust purification system for an internal combustion engine has a hydrogen concentration sensor (2) disposed upstream of a catalytic converter (1) in the engine exhaust system to detect a hydrogen concentration in the exhaust gas. An optimum combustion air-fuel ratio is then estimated based on the detected hydrogen concentration.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS
This application is a national phase application of International Application No. PCT/IB2007/000457, filed Feb. 26, 2007, and claims the priority of Japanese Application No. 2006-052540, filed Feb. 28, 2006, the contents of both of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an exhaust purification system for an internal combustion engine and a control method of the exhaust purification system.
2. Description of the Related Art
As described in JP-A-H6-307271, an oxygen concentration sensor is disposed upstream of a catalytic converter in the engine exhaust system to detect an oxygen concentration in the exhaust gas and estimate the optimum air-fuel ratio based on the detected oxygen concentration.
When the air-fuel ratio is leaner than the stoichiometric ratio (i.e., when the air-fuel ratio increases), the oxygen concentration in the exhaust gas increases more noticeably. This ensures a more accurate estimation of the optimum air-fuel ratio. However, when the air-fuel ratio is richer than the stoichiometric ratio, the oxygen concentration in the exhaust gas decreases to almost zero and then shows less noticeable change than the air-fuel ratio does. This makes the accurate estimation of the optimum air-fuel ratio more difficult.
DISCLOSURE OF THE INVENTION
The present invention provides an exhaust purification system for an internal combustion engine and a method of controlling the exhaust purification system, which allow a more accurate estimation of the optimum air-fuel ratio when the ratio is richer than the stoichiometric ratio.
A first aspect of the invention relates to an exhaust purification system for an internal combustion engine. The exhaust purification system for an internal combustion engine has an upstream hydrogen concentration sensor disposed upstream of a catalytic converter in the engine exhaust system to detect the hydrogen concentration in the exhaust gas and estimate an optimum air-fuel ratio based on the detected hydrogen concentration.
In the exhaust purification system according to the first aspect of the invention, the catalytic converter is a three-way catalytic converter and a downstream hydrogen concentration sensor is disposed downstream of the three-way catalytic converter. Also, when a measured or an estimated temperature in the three-way catalytic converter is lower than a prescribed temperature, the degree of deterioration of the three-way catalytic converter may be estimated based on the difference between upstream and downstream hydrogen concentrations detected by the upstream and downstream hydrogen concentration sensors, respectively.
As described above, the catalytic converter is a three-way catalytic converter and the downstream hydrogen concentration sensor is disposed downstream of the three-way catalytic converter. When the measured or estimated temperature in the three-way catalytic converter is equal to or higher than the prescribed temperature and the air-fuel ratio in the exhaust gas entering the three-way catalytic converter is equal to or richer than a stoichiometric ratio, sulfur poisoning of the three-way catalytic converter may be determined based on the difference between the upstream and downstream hydrogen concentrations detected by the upstream and downstream hydrogen concentration sensors, respectively.
When it is determined that sulfur poisoning of the three-way catalytic converter has occurred, the measured or estimated temperature in the three-way catalytic converter may be controlled to remain equal or higher than the prescribed temperature, while the air-fuel ratio in the exhaust gas entering the three-way catalytic converter is controlled to remain equal to or richer than the stoichiometric ratio.
If it is determined that sulfur poisoning of the three-way catalytic converter has occurred, when the vehicle stops at idle and the measured or estimated temperature in the three-way catalytic converter remaining equal to or higher than the prescribed temperature, the air-fuel ratio in the exhaust gas entering the three-way catalytic converter may be controlled to be leaner than the stoichiometric ratio.
The exhaust purification system according to the first aspect of the invention may further include an oxygen concentration sensor disposed upstream of the catalytic converter in the engine exhaust system.
In the exhaust purification system according to the first aspect of the invention, when the air-fuel ratio is richer than the stoichiometric ratio, an estimation of the optimum air-fuel ratio may depend on the hydrogen concentration sensor.
When the air-fuel ratio is leaner than the stoichiometric ratio, an estimation of the optimum air-fuel ratio may depend on the oxygen concentration sensor.
The exhaust purification system according to the first aspect of the invention may have no catalytic converter disposed upstream of the upstream hydrogen concentration sensor.
A second aspect of the invention relates to a method of controlling the exhaust purification system for an internal combustion engine. The control method includes: detecting the hydrogen concentration contained in the exhaust gas upstream of a catalytic converter, disposed in the engine exhaust system; and estimating the optimum air-fuel ratio based on the detected hydrogen concentration.
In the exhaust purification system for an internal combustion engine according to the first aspect of the invention, when the air-fuel ratio is rich (as the air-fuel ratio decreases), the hydrogen concentration in the exhaust gas upstream of the catalytic converter increases more noticeably. Therefore, the detection of the hydrogen concentration in the exhaust gas with the upstream hydrogen concentration sensor disposed upstream of the catalytic converter in the engine exhaust system permits a more accurate estimation of the optimum air-fuel ratio, when the ratio is richer than the stoichiometric ratio.
In the exhaust purification system according to the first aspect of the invention, the catalytic converter may be a three-way catalytic converter and the downstream hydrogen concentration sensor may be disposed downstream of the three-way catalytic converter. With such configuration, in the three-way catalytic converter, a water vapor reforming reaction occurs in which hydrocarbons in the exhaust gas react with water vapor. In addition a water gas-shift reaction occurs in which carbon monoxide in the exhaust gas reacts with water vapor. However, hydrogen is formed as a product in both reactions. Therefore, when the measured or estimated temperature in the three-way catalytic converter is lower than the prescribed temperature, the difference between the upstream and downstream hydrogen concentrations detected by the upstream and downstream hydrogen concentration sensors, respectively, indicates the activity of the aforementioned water vapor reforming reaction and water gas-shift reaction. The less active these reactions are, the greater the extent of deterioration of three-way catalytic converter. Thus, the degree of deterioration of the three-way catalytic converter may be estimated.
In the exhaust purification system according to the first aspect of the invention, the catalytic converter may be a three-way catalytic converter and the downstream hydrogen concentration sensor may be disposed downstream of the three-way catalytic converter. With such configuration, when the measured or estimated temperature in the three-way catalytic converter is equal to or higher than the prescribed temperature and the air-fuel ratio in the exhaust gas entering the three-way catalytic converter is equal to or richer than the stoichiometric ratio, the three-way catalytic converter releases SOX if SOX is adsorbed therein. The SOX emissions react with hydrogen in the exhaust gas to form hydrogen sulfide. Therefore, in the three-way catalytic converter, hydrogen is formed in the described water vapor reforming reaction and water gas-shift reaction, while part of the hydrogen is consumed to form hydrogen sulfide. Thus, sensing the difference between the upstream and downstream hydrogen concentrations, detected by the upstream and downstream hydrogen concentration sensors, respectively, allows to estimate whether the hydrogen is consumed to form hydrogen sulfide. If consumption of hydrogen due to the formation of hydrogen sulfide is observed, it may be determined that sulfur poisoning of the three-way catalytic converter has occurred.
In the exhaust purification system according to the first aspect of the invention, when it is determined that sulfur poisoning of the three-way catalytic converter has occurred, the measured or estimated temperature in the three-way catalytic converter may be controlled to remain equal or higher than the prescribed temperature, while the air-fuel ratio of the exhaust gas entering the three-way catalytic converter may be controlled to remain equal to or richer than the stoichiometric ratio. With such configuration, if SOX having been stored in the three-way catalytic converter can be all emitted therefrom, this indicates no further formation of hydrogen sulfide in the three-way catalytic converter and accordingly, no hydrogen consumption. Therefore, it is determined that sulfur poisoning of the three-way catalytic converter has not occurred.
In the exhaust purification system according to the first aspect of the invention, if it is determined that sulfur poisoning of the three-way catalytic converter has occurred, if the vehicle stops at idle and the measured or estimated temperature in the three-way catalytic converter remains equal to or higher than the prescribed temperature, the three-way catalytic converter continues to produce SOX emissions. The SOX emissions react with hydrogen to form hydrogen sulfide, which is released to the air and possibly produces an offensive odor. Thus, the air-fuel ratio of the exhaust gas entering the three-way catalytic converter is controlled to be leaner than the stoichiometric ratio to reduce the SOX emissions from the three-way catalytic converter even if SOX is stored therein.
BRIEF DESCRIPTION OF THE DRAWINGS
The foregoing and further objects, features and advantages of the invention will become apparent from the following description of preferred embodiments with reference to the accompanying drawings, wherein like numerals are used to represent like elements and wherein:
FIG. 1 is a schematic diagram of an exhaust purification system for an internal combustion engine according to one embodiment of the invention.
FIG. 2 is a graph illustrating changes in hydrogen and CO concentrations versus air-fuel ratio.
FIG. 3 is a flowchart of a control process for the exhaust purification system for an internal combustion engine according to the embodiment of the invention.
 DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
FIG. 1 is a schematic diagram of an exhaust purification system for an internal combustion engine according to one embodiment of the invention. A three-way catalytic converter 1 is disposed in the engine exhaust system. An upstream hydrogen concentration sensor 2 is disposed upstream of the three-way catalytic converter 1. A downstream hydrogen concentration sensor 3 is disposed downstream of the three-way catalytic converter 1.
In the embodiment of the invention, the internal combustion engine is predominantly designed to perform a homogenous combustion process with the stoichiometric ratio. The three-way catalytic converter 1 is designed to purity the exhaust gas burned at the stoichiometric ratio in a desired manner. However, under a high-load or high-speed operating condition, the air-fuel ratio may be enriched with respect to the stoichiometric ratio to increase engine output. Likewise, under a low-load or low-speed operating condition, the air-fuel ratio may be made leaner with respect to the stoichiometric ratio to reduce fuel consumption. Under these conditions, an O2 storage capacity of the three-way catalytic converter 1 helps maintain the air-fuel ratio in the exhaust gas within the three-way catalytic converter 1 at around the stoichiometric ratio.
In general, the oxygen concentration sensor is disposed in the engine exhaust system to detect the oxygen concentration of the exhaust gas and estimate the optimum air-fuel ratio based on the detected oxygen concentration. However, the oxygen concentration in the engine exhaust system is almost zero when the air-fuel ratio is richer than the stoichiometric ratio. Under such condition, the oxygen concentration varies more slightly than the air-fuel ratio, which makes an accurate estimation of the optimum air-fuel ratio more difficult.
A solid line in the graph of FIG. 2 illustrates a relationship between air-fuel ratio and hydrogen concentration. As the graph shows, in the range of richer air-fuel ratio than the stoichiometric ratio, as the air-fuel ratio is richer (as the air-fuel ratio decreases), the hydrogen concentration increases more noticeably. Thus, the changes in hydrogen concentration are more apparent than the corresponding change in the air-fuel ratio. Therefore, in the embodiment of the invention, the optimum air-fuel ratio is estimated based on the hydrogen concentration in the exhaust gas, which is detected by the upstream hydrogen concentration sensor 2. In this embodiment, the optimum air-fuel ratio is more accurately estimated of particularly when the air-fuel ratio is rich. Based on this accurate estimation, the amount of fuel to be injected may be controlled to obtain the desired air-fuel ratio.
In contrast when the air-fuel ratio is lean, the hydrogen concentration shows more slight changes than the air-fuel ratio does. Even in a lean air-fuel ratio, the estimation of the optimum air-fuel ratio may be based on the hydrogen concentration detected by the upstream hydrogen concentration sensor 2. In addition to the upstream hydrogen concentration sensor 2, the oxygen concentration sensor is also disposed upstream of the three-way catalytic converter 1 to detect the oxygen concentration in the exhaust gas. The detected oxygen concentration is more noticeable when the air-fuel ration is leaner (as the air-fuel ratio increases). In other words, the oxygen concentration shows greater changes than the air-fuel ratio does. Thus, when the air-fuel ratio is lean, the estimation of the optimum air-fuel ratio may be based on the oxygen concentration detected by the oxygen sensor.
When the exhaust gas passes through a catalytic converter having an oxidation function, such as three-way catalytic converter and NOX storage reduction catalytic converter, a water vapor reforming reaction occurs in which hydrocarbons in the exhaust gas react with water vapor to form hydrogen, as shown in formula (1). In addition, a water gas-shift reaction occurs in which carbon monoxide in the exhaust gas reacts with water vapor to form hydrogen, as shown in formula (2).
CH2+H2O→CO+2H2  (1)
CO+H2O→CO2+H2  (2)
It is therefore preferable to detect the hydrogen concentration in the exhaust gas, which has not yet passed through the catalytic converter, by the upstream hydrogen concentration sensor 2. Thus, in the embodiment of the invention, a catalytic converter is not disposed upstream of the upstream hydrogen concentration sensor 2.
SOX in the exhaust gas reacts with barium or potassium contained in the three-way catalytic converter 1 and the SOX is stored therein (hereinafter called as sulfur poisoning). This not only lowers the function of the noble metal catalyst contained in the three-way catalytic converter 1, thus increasing the temperature at which the activation occurs, but also lowers the O2 storage capacity of ceria contained in the three-way catalytic converter 1.
The three-way catalytic converter 1, which stores the SOX, releases SOX if the temperature in the three-way catalytic converter 1 is equal to or higher than a prescribed temperature and the oxygen concentration in the three-way catalytic converter 1 decreases. For example, under a high-load or high-speed driving condition, the high exhaust gas temperature causes the temperature in the three-way catalytic converter 1 to increase to or exceed the prescribed temperature. At the same time, the air-fuel ratio is equal to or richer than the stoichiometric ratio, under which the oxygen concentration in the exhaust gas decreases. Thereby, SOX is released automatically from the three-way catalytic converter 1.
In the embodiment of the invention, the upstream and downstream hydrogen concentration sensors 2 and 3 are used to determine the extent of deterioration of the three-way catalytic converter 1 or to solve the sulfur poisoning in accordance with the flowchart shown in FIG. 3.
The process beings in step S101 to determine whether a measured temperature T (estimated temperature) in the three-way catalytic converter 1 is equal to or higher than a prescribed temperature T1. If the determination is false, the three-way catalytic converter 1 will not release SOX. Then, the process goes to step S102 to calculate a difference C between the upstream and downstream hydrogen concentrations C1 and C2 detected by the upstream and downstream hydrogen concentration sensors 2 and 3, respectively. The difference C depends on the amount of hydrogen in the aforementioned water vapor reforming and water gas shift reactions.
If these reactions are active, the extent of deterioration of the three-way catalytic converter 1 is determined to be minimal. If not active, the extent of deterioration of the three-way catalytic converter 1 is significant. Then, the process goes to step S103 to determine whether a value, which is obtained by correcting the difference C between the upstream and downstream hydrogen concentrations C1 and C2 with a correction coefficient, k, is equal to or lower than a prescribed concentration D. If the degree of deterioration of the three-way catalytic converter 1 is determined to remain unchanged, as the exhaust gas contains more CH2 and CO, that amounts of which are estimated based on the air-fuel ratio, or as the three-way catalytic converter 1 has a higher temperature, the water vapor reforming reaction and the water gas shift reaction are more active, and therefore the correction coefficient k decreases. A dotted line in FIG. 2 illustrates a relationship between air-fuel ratio and CO concentration.
The difference C corrected with the correction coefficient k is independent of the amounts of CH2 and CO currently contained in the exhaust gas, and the current temperature of the three-way catalytic converter 1. The difference C is inversely proportional to the current degree of deterioration of the three-way catalytic converter 1. Thus, if the determination in step S103 is true, there is significant deterioration of the three-way catalytic converter 1. Furthermore, if the determination in step S103 is true multiple times consecutively, the three-way catalytic converter 1 may be determined to be deteriorated greatly.
In accordance with the flowchart shown in FIG. 3, the deterioration of the three-way catalytic converter 1 is determined directly from the oxidation-reduction reaction that occurs in the three-way catalytic converter 1, such as the water vapor reforming reaction and water gas-shift reaction. This ensures more accurate determination of the deterioration of the three-way catalytic converter 1, compared to the indirect determination from, for example, a decrease in O2 storage capacity.
On the other hand, if the determination in step S101 is true, the process goes to step S105 to calculate the difference C between the upstream and downstream hydrogen concentrations C1 and C2 in the same manner as step S102. In step S305, under a high-load or high-speed driving condition, the three-way catalytic converter 1 has a high temperature, while the air-fuel ratio is equal to or richer than the stoichiometric ratio. Therefore, if sulfur poisoning of the three-way catalytic converter 1 has occurred, it produces SOX emissions.
The SOX emissions react with hydrogen to form hydrogen sulfide, as shown by the following formula (3).
SO2+3H2→H2S+2H2O  (3)
Then, the process goes to step S106 to determine whether or not the difference C between the upstream and downstream hydrogen concentrations C1 and C2, which is calculated in step S105, is approximately equal to a hydrogen concentration C′ based on the amount of hydrogen formed by the water vapor reforming reaction and the water gas-shift reaction. The hydrogen concentration C′ is estimated by taking into account the amounts of CH2 and CO currently contained in the exhaust gas, the current temperature of the three-way catalytic converter 1, and the current degree of deterioration of the catalytic converter 1. The true determination in step S106 indicates that there is no hydrogen being consumption through the formation of hydrogen sulfide. In other words, it is determined whether the three-way catalytic converter 1 is not releasing SOX.
If the determination in step S106 is true, it is determined that sulfur poisoning of the three-way catalytic converter 1 has not occurred. The process ends the determination in accordance with the flowchart, as shown in FIG. 3. Thus, the air-fuel ratio is not necessarily enriched or leaned, and the amount of oxygen stored in the three-way catalytic converter 1 does not excessively fluctuate, as will be discussed below.
In contrast, a false determination in step S106 indicates that hydrogen is being consumed to form hydrogen sulfide. In other words, it is determined that sulfur poisoning of the three-way catalytic converter 1 has occurred because to the release of SOX. Then, in accordance with the flowchart, the process goes to step S107 to determine whether the vehicle has stopped. If the determination is false, that is, the vehicle is in motion, the process goes to step S108 to enrich the air-fuel ratio with respect to the stoichiometric ratio, so that the three-way catalytic converter 1 continues to release SOX. However, hydrogen sulfide, which is formed while the vehicle is moving, does not enter the interior of the vehicle.
Nonetheless, when the vehicle stops immediately after the high-load or high-speed driving, the SOX emissions from the three-way catalytic converter 1 cause formation of hydrogen sulfide, which enters the interior of the vehicle. Thus, the driver and any other occupants may smell an offensive odor. Therefore, if the determination in step S107 is true, the process goes to step S109 to lean the air-fuel ratio to reduce SOX emissions. Thereby, hydrogen sulfide formation is less likely to occur.
In steps S102 and S105 of the flowchart, the upstream hydrogen concentration sensor 2 is designed to detect the upstream hydrogen concentration C1 in the three-way catalytic converter 1. Alternatively, should an optimum air-fuel ratio be estimated by means other than the above, such as oxygen sensor, the upstream hydrogen concentration C1 may be determined based on the optimum estimated air-fuel ratio. For example, when the air-fuel ratio is leaner than the stoichiometric ratio, the oxygen concentration sensor may be used to estimate the upstream hydrogen concentration C1.
While the invention has been described with reference to what are considered to be preferred embodiments thereof it is to be understood that the invention is not limited to the disclosed embodiments or constructions. On the contrary, the invention is intended to cover various modifications and equivalent arrangements. In addition, while the various elements of the disclosed invention are shown in various combinations and configurations, which are exemplary, other combinations and configurations, including more, less or only a single element, are also within the scope of the appended claims.

Claims (6)

1. An exhaust purification system for an internal combustion engine comprising:
a three-way catalytic converter provided in an exhaust system of the internal combustion engine;
an upstream hydrogen concentration sensor, disposed upstream of the catalytic converter, that detects a hydrogen concentration in the exhaust gas upstream of the catalytic converter; and
a downstream hydrogen concentration sensor, disposed downstream of the catalytic converter, that detects a hydrogen concentration in the exhaust gas downstream of the catalytic converter,
wherein an optimum combustion air-fuel ratio is estimated based on the detected upstream hydrogen concentration, and
wherein when a measured or an estimated temperature of the catalytic converter is below a threshold temperature, a degree of deterioration of the catalytic converter is estimated based on the difference between the detected upstream hydrogen concentration and the detected downstream hydrogen concentration.
2. The exhaust purification system for an internal combustion engine according to claim 1, further comprising an oxygen concentration sensor, disposed upstream of the catalytic converter in the engine exhaust system, that detects an oxygen concentration in the exhaust gas.
3. The exhaust purification system for an internal combustion engine according to claim 2, wherein the optimum combustion air-fuel ratio is estimated based on the detected hydrogen concentration in the exhaust gas when a combustion air-fuel ratio is richer than the stoichiometric ratio.
4. The exhaust purification system for an internal combustion engine according to claim 2, wherein the optimum combustion air-fuel ratio is estimated based on the detected hydrogen concentration in the exhaust gas when a combustion air-fuel ratio is leaner than the stoichiometric ratio.
5. The exhaust purification system for an internal combustion engine according to claim 2, wherein the optimum air-fuel ratio is estimated based on the detected oxygen concentration, and the hydrogen concentration in the exhaust gas upstream of the catalytic converter is estimated based the estimated optimum combustion air-fuel ratio.
6. A control method of an exhaust purification system for an internal combustion engine comprising:
detecting a hydrogen concentration contained in exhaust gas upstream of a three-way catalytic converter disposed in the engine exhaust system;
estimating an optimum combustion air-fuel ratio based on the detected upstream hydrogen concentration; and
detecting a hydrogen concentration contained in the exhaust gas downstream of the catalytic converter,
wherein when a measured or an estimated temperature of the catalytic converter is below a threshold temperature, a degree of deterioration of the catalytic converter is estimated based on the difference between the detected upstream hydrogen concentration and the detected downstream hydrogen concentration.
US12/280,564 2006-02-28 2007-02-26 Exhaust purification system for internal combustion engine and control method of the exhaust purification system Expired - Fee Related US8161729B2 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP2006-052540 2006-02-28
JP2006052540A JP4371114B2 (en) 2006-02-28 2006-02-28 Exhaust gas purification device for internal combustion engine
PCT/IB2007/000457 WO2007099429A1 (en) 2006-02-28 2007-02-26 Exhaust purification system for internal combustion engine and control method of the exhaust purification system

Publications (2)

Publication Number Publication Date
US20090019832A1 US20090019832A1 (en) 2009-01-22
US8161729B2 true US8161729B2 (en) 2012-04-24

Family

ID=38226379

Family Applications (1)

Application Number Title Priority Date Filing Date
US12/280,564 Expired - Fee Related US8161729B2 (en) 2006-02-28 2007-02-26 Exhaust purification system for internal combustion engine and control method of the exhaust purification system

Country Status (6)

Country Link
US (1) US8161729B2 (en)
EP (1) EP1989415B1 (en)
JP (1) JP4371114B2 (en)
CN (1) CN101360895B (en)
DE (1) DE602007008369D1 (en)
WO (1) WO2007099429A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20160312731A1 (en) * 2015-04-27 2016-10-27 Mitsubishi Jidosha Kogyo Kabushiki Kaisha Engine controlling apparatus

Families Citing this family (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP4836021B2 (en) 2007-07-24 2011-12-14 トヨタ自動車株式会社 Cylinder air-fuel ratio variation abnormality detecting device and method for multi-cylinder internal combustion engine
JP5018550B2 (en) 2008-02-27 2012-09-05 トヨタ自動車株式会社 Fuel reformer
WO2010064302A1 (en) * 2008-12-02 2010-06-10 トヨタ自動車株式会社 Control device for internal combustion engine
JP5110205B2 (en) * 2010-11-17 2012-12-26 トヨタ自動車株式会社 Control device for internal combustion engine
JP5660945B2 (en) * 2011-03-18 2015-01-28 ダイハツ工業株式会社 Catalyst deterioration determination device for internal combustion engine
CA2906162C (en) * 2013-03-14 2022-08-23 Paul Jablonski Implantable medical devices comprising bio-degradable alloys with enhanced degradation rates
US20150033709A1 (en) * 2013-07-31 2015-02-05 General Electric Company Sulfur sensor for engine exhaust
JP6144652B2 (en) * 2014-07-23 2017-06-07 トヨタ自動車株式会社 Exhaust gas purification device for internal combustion engine
DE102014016447B4 (en) * 2014-11-06 2023-05-11 Andreas Döring Method and control device for operating an internal combustion engine
JP6597677B2 (en) * 2017-03-10 2019-10-30 トヨタ自動車株式会社 Exhaust gas purification device for internal combustion engine
CN111520242B (en) * 2020-04-24 2022-11-11 深圳市元征科技股份有限公司 Air-fuel ratio adjusting method and device
CN112267929B (en) * 2020-10-16 2022-01-21 潍柴动力股份有限公司 Method for saving precious metal consumption of three-way catalyst, tail gas treatment system and vehicle
JP2024010982A (en) * 2022-07-13 2024-01-25 トヨタ自動車株式会社 Exhaust emission control device for internal combustion engine

Citations (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4141326A (en) * 1977-03-11 1979-02-27 The Bendix Corporation Closed loop control system for hydrogen fuelled engine
US4844788A (en) 1987-11-04 1989-07-04 Kabushiki Kaisha Toyota Chuo Kenkyusho Wide-range air/fuel ratio sensor and detector using the same
EP0530655A2 (en) 1991-08-31 1993-03-10 LAMTEC Mess- und Regeltechnik für Feuerungen GmbH & Co. KG Method and apparatus for controlling an internal combustion engine and testing its catalytic converter
JPH06307271A (en) 1993-04-23 1994-11-01 Mazda Motor Corp Air-fuel ratio controller for engine
JP2000161107A (en) 1998-12-01 2000-06-13 Mitsubishi Motors Corp Exhaust emission control device for internal combustion engine
US6220017B1 (en) * 1998-06-26 2001-04-24 Nissan Motor Co., Ltd. Exhaust emission control system for internal combustion engine
JP2003027924A (en) 2001-07-17 2003-01-29 Nissan Motor Co Ltd Exhaust emission control device
EP1298304A2 (en) 2001-09-26 2003-04-02 Robert Bosch Gmbh Regulation method for the air to fuel ratio for a combustion engine
US6684628B2 (en) * 2000-04-11 2004-02-03 Dmc2 Degussa Metals Catalysts Cerdec Ag Process for checking the operatability of a nitrogen oxide storage catalyst
JP2005171982A (en) 2003-11-18 2005-06-30 Toyota Motor Corp Air-fuel ratio control system
WO2005066472A1 (en) 2004-01-06 2005-07-21 Toyota Jidosha Kabushiki Kaisha Apparatus for evaluating deterioration condition of catalyst of internal combustion engine
JP2005240712A (en) 2004-02-27 2005-09-08 Mitsubishi Heavy Ind Ltd Gas engine
JP2005337127A (en) 2004-05-27 2005-12-08 Toyota Motor Corp Internal combustion engine
WO2006093357A1 (en) 2005-03-04 2006-09-08 Toyota Jidosha Kabushiki Kaisha Exhaust gas purification apparatus for internal combustion engine
US7111452B2 (en) * 2004-02-26 2006-09-26 Mazda Motor Corporation Control device of hydrogen engine
US20060248876A1 (en) * 2005-05-04 2006-11-09 Taxon Morse N Selective catalytic reduction exhaust after-treatment
WO2006123564A1 (en) 2005-05-19 2006-11-23 Toyota Jidosha Kabushiki Kaisha Exhaust gas purifying device for internal combustion engine
US20080041034A1 (en) * 2006-05-10 2008-02-21 Suzuki Motor Corporation Exhaust gas purification for a hydrogen engine

Patent Citations (20)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4141326A (en) * 1977-03-11 1979-02-27 The Bendix Corporation Closed loop control system for hydrogen fuelled engine
US4844788A (en) 1987-11-04 1989-07-04 Kabushiki Kaisha Toyota Chuo Kenkyusho Wide-range air/fuel ratio sensor and detector using the same
EP0530655A2 (en) 1991-08-31 1993-03-10 LAMTEC Mess- und Regeltechnik für Feuerungen GmbH & Co. KG Method and apparatus for controlling an internal combustion engine and testing its catalytic converter
JPH06307271A (en) 1993-04-23 1994-11-01 Mazda Motor Corp Air-fuel ratio controller for engine
US6220017B1 (en) * 1998-06-26 2001-04-24 Nissan Motor Co., Ltd. Exhaust emission control system for internal combustion engine
JP2000161107A (en) 1998-12-01 2000-06-13 Mitsubishi Motors Corp Exhaust emission control device for internal combustion engine
US6684628B2 (en) * 2000-04-11 2004-02-03 Dmc2 Degussa Metals Catalysts Cerdec Ag Process for checking the operatability of a nitrogen oxide storage catalyst
JP2003027924A (en) 2001-07-17 2003-01-29 Nissan Motor Co Ltd Exhaust emission control device
EP1298304A2 (en) 2001-09-26 2003-04-02 Robert Bosch Gmbh Regulation method for the air to fuel ratio for a combustion engine
JP2003120383A (en) 2001-09-26 2003-04-23 Robert Bosch Gmbh Method of setting fuel/air mixture for internal combustion engine
JP2005171982A (en) 2003-11-18 2005-06-30 Toyota Motor Corp Air-fuel ratio control system
WO2005066472A1 (en) 2004-01-06 2005-07-21 Toyota Jidosha Kabushiki Kaisha Apparatus for evaluating deterioration condition of catalyst of internal combustion engine
US7111452B2 (en) * 2004-02-26 2006-09-26 Mazda Motor Corporation Control device of hydrogen engine
JP2005240712A (en) 2004-02-27 2005-09-08 Mitsubishi Heavy Ind Ltd Gas engine
JP2005337127A (en) 2004-05-27 2005-12-08 Toyota Motor Corp Internal combustion engine
WO2006093357A1 (en) 2005-03-04 2006-09-08 Toyota Jidosha Kabushiki Kaisha Exhaust gas purification apparatus for internal combustion engine
US7694512B2 (en) * 2005-03-04 2010-04-13 Toyota Jidosha Kabushiki Kaisha Exhaust gas purification apparatus for internal combustion engine
US20060248876A1 (en) * 2005-05-04 2006-11-09 Taxon Morse N Selective catalytic reduction exhaust after-treatment
WO2006123564A1 (en) 2005-05-19 2006-11-23 Toyota Jidosha Kabushiki Kaisha Exhaust gas purifying device for internal combustion engine
US20080041034A1 (en) * 2006-05-10 2008-02-21 Suzuki Motor Corporation Exhaust gas purification for a hydrogen engine

Non-Patent Citations (5)

* Cited by examiner, † Cited by third party
Title
European Office Action dated Jan. 12, 2009.
European Office Action dated May 6, 2009.
European Office Action issued on Sep. 24, 2009 for EP Appl. No. 07 733 905.9.
Japanese Office Action dated Nov. 26, 2008.
Notification of the First Office Action for JP 2007800015062 dated Feb. 5, 2010.

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20160312731A1 (en) * 2015-04-27 2016-10-27 Mitsubishi Jidosha Kogyo Kabushiki Kaisha Engine controlling apparatus
US10215123B2 (en) * 2015-04-27 2019-02-26 Mitsubishi Jidosha Kogyo Kabushiki Kaisha Engine controlling apparatus

Also Published As

Publication number Publication date
CN101360895B (en) 2010-11-17
WO2007099429A1 (en) 2007-09-07
CN101360895A (en) 2009-02-04
JP2007231779A (en) 2007-09-13
EP1989415A1 (en) 2008-11-12
EP1989415B1 (en) 2010-08-11
US20090019832A1 (en) 2009-01-22
DE602007008369D1 (en) 2010-09-23
JP4371114B2 (en) 2009-11-25

Similar Documents

Publication Publication Date Title
US8161729B2 (en) Exhaust purification system for internal combustion engine and control method of the exhaust purification system
JP4284087B2 (en) Exhaust gas purification device for internal combustion engine
US7793489B2 (en) Fuel control for robust detection of catalytic converter oxygen storage capacity
US6446429B2 (en) Air-fuel ratio control of engine
US6405527B2 (en) Fuel supply conrol system for internal combustion engine
US9670819B2 (en) Catalyst deterioration determination system
JP5029718B2 (en) Exhaust gas purification device for internal combustion engine
US20060230749A1 (en) Exhaust gas control apparatus for internal combustion engine
KR101500349B1 (en) APPARATUS AND METHOD FOR DETECTING AGED OF LEAN NOx TRAP CATALYST
US20080115486A1 (en) Flexible fuel tolerant catalytic converter diagnostic method
US20040159094A1 (en) Automotive catalyst oxygen storage capacity diagnostic
JP2008303759A (en) Exhaust emission control device of internal combustion engine
US7513105B2 (en) Exhaust gas purifying system and abnormality determining method therefor
EP1651845A1 (en) Exhaust gas control apparatus for internal combustion engine
US8186147B2 (en) Catalyst deterioration-determination device and method and engine control unit
JP2009299557A (en) Catalyst deterioration-determination device
US7467511B2 (en) Emission control strategy for lean idle
JP4890209B2 (en) Exhaust gas purification device for internal combustion engine
JP5022997B2 (en) Catalyst deterioration judgment device
JP4190430B2 (en) Oxygen sensor abnormality diagnosis device
GB2380427A (en) A method for monitoring the efficiency of an exhaust gas treatment device.
JP2007303361A (en) Exhaust emission control system for internal combustion engine
KR100612967B1 (en) Oxygen sensor deterioration compensation control method
JP2005139921A (en) Exhaust emission control system of internal combustion engine
JP3610798B2 (en) Air-fuel ratio control device for internal combustion engine

Legal Events

Date Code Title Description
AS Assignment

Owner name: TOYOTA JIDOSHA KABUSHIKI KAISHA, JAPAN

Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNOR:KATOH, KENJI;REEL/FRAME:021433/0275

Effective date: 20080424

STCF Information on status: patent grant

Free format text: PATENTED CASE

FPAY Fee payment

Year of fee payment: 4

FEPP Fee payment procedure

Free format text: MAINTENANCE FEE REMINDER MAILED (ORIGINAL EVENT CODE: REM.); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY

LAPS Lapse for failure to pay maintenance fees

Free format text: PATENT EXPIRED FOR FAILURE TO PAY MAINTENANCE FEES (ORIGINAL EVENT CODE: EXP.); ENTITY STATUS OF PATENT OWNER: LARGE ENTITY

STCH Information on status: patent discontinuation

Free format text: PATENT EXPIRED DUE TO NONPAYMENT OF MAINTENANCE FEES UNDER 37 CFR 1.362

FP Lapsed due to failure to pay maintenance fee

Effective date: 20200424